This Week’s Sky at a Glance

Supernova in M82 peaks at magnitude 10.5, nicely visible in amateur telescopes. Catch it before the waxing Moon starts brightening the sky after about February 3rd. See our updated article, Supernova in M82 Reaches Its Peak.


Back in the evening sky, the waxing Moon passes Mercury after sundown.

Friday, January 31

  • In twilight, look very low above the west-southwest horizon for the thin waxing crescent Moon with Mercury to its upper left, as shown here.

    Saturday, February 1

  • Mercury now shines below the thin crescent Moon low in the west-southwest after sunset, as shown here.

  • Jupiter's moon Ganymede casts its tiny black shadow onto Jupiter from 5:42 to 8:22 p.m. EST. Jupiter's Great Red Spot crosses the planet's central meridian around 11:48 p.m. EST (8:48 p.m. PST).

    Sunday, February 2

  • In Taurus, in the familiar area of the Hyades, two lesser-known clusters await your scope — or even good binoculars if you have a dark sky. NGC 1647 and sparser NGC 1746 lie exactly on the line from Aldebaran to Beta (β) Tauri (Elnath). See Gary Seronik's Binocular Highlight in the February Sky & Telescope, page 45.

    Monday, February 3

  • The crescent Moon this evening shines to the left of the Great Square of Pegasus. The Great Square is tipped up onto one corner, as it always is at this time of year.

    Tuesday, February 4

  • Jupiter's moon Io disappears behind Jupiter's western limb around 8:57 p.m. EST. Twenty minutes later, Jupiter's Great Red Spot crosses the planet's central meridian. Finally, Io reappears out of eclipse from Jupiter's shadow, just east of the planet, around 11:56 p.m. EST (8:56 p.m. PST).

    Wednesday, February 5

  • The biggest and brightest asteroids, 1 Ceres and 4 Vesta respectively, are only about 4° apart in eastern Virgo in the early morning hours. They're magnitude 8.2 and 7.2, respectively. Article and chart. (In the February Sky & Telescope, page 50, the labels for Ceres and Vesta on the chart are swapped; switch them back.)

    Thursday, February 6

  • First-quarter Moon. The Moon shines at the Aries-Taurus border, below the Pleiades throughout the evening hours.

    Friday, February 7

  • This season, Jupiter turns the Winter Triangle into a bigger, brighter Winter Diamond! Its bottom is Sirius, its two side corners are Betelgeuse and Procyon, and Jupiter forms its top. The diamond tilts leftward in early evening, then stands vertically in the south around 10 p.m. (depending on your location).

    Saturday, February 8

  • Look to the right of the Moon after dinnertime for Aldebaran. Below the Moon stands Orion.


    Want to become a better astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope.

    This is an outdoor nature hobby. For an easy-to-use constellation guide covering the whole evening sky, use the big monthly map in the center of each issue of Sky & Telescope, the essential guide to astronomy. Or download our free Getting Started in Astronomy booklet (which only has bimonthly maps).

    The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6 — which may sound like a lot, but that's less than one star in an entire telescopic field of view, on average. By comparison, Sky Atlas 2000.0 plots 81,312 stars to magnitude 8.5, typically one or two stars per telescopic field. Both atlases include many hundreds of deep-sky targets — galaxies, star clusters, and nebulae — to hunt among the stars.
    Sky & Telescope

    Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts). The standards are the little Pocket Sky Atlas, which shows stars to magnitude 7.6; the larger and deeper Sky Atlas 2000.0 (stars to magnitude 8.5); and once you know your way around, the even larger Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope.

    You'll also want a good deep-sky guidebook, such as Sue French's Deep-Sky Wonders collection (which includes its own charts), Sky Atlas 2000.0 Companion by Strong and Sinnott, the bigger Night Sky Observer's Guide by Kepple and Sanner, or the beloved if dated Burnham's Celestial Handbook.

    Can a computerized telescope replace charts? Not for beginners, I don't think, and not on mounts and tripods that are less than top-quality mechanically (able to point with better than 0.2° repeatability, which means fairly heavy and expensive). As Terence Dickinson and Alan Dyer say in their invaluable Backyard Astronomer's Guide, "A full appreciation of the universe cannot come without developing the skills to find things in the sky and understanding how the sky works. This knowledge comes only by spending time under the stars with star maps in hand."


    This Week's Planet Roundup

    Gibbous Mars was still just 7.1 arcseconds from pole to pole on January 6th when Don Parker in Florida imaged it with a 16-inch reflector. South is up. Note the North Polar Cap with hints of a rift already developing, morning clouds near the following (celestial east; right-hand) limb, haze visible over the dark Syrtis Major region on the opposite (preceding) limb, and in the south, distinctive Sinus Sabaeus ending with two-pronged Sinus Meridiani.
    Donald C. Parker

    Mercury is visible in evening twilight, low in the west-southwest. It fades rapidly, from magnitude –0.6 to +0.7 this week.

    Venus (magnitude –4.8) shines brightly in the dawn; look southeast. In a telescope Venus is a crescent, thickening from 14% to 19% sunlit this week.

    Mars (magnitude +0.2, in Virgo) rises around 11 p.m. It's just 4° or 5° from lesser Spica to its lower right. Compare their colors. They're highest in the south around 4 a.m., with Spica now under Mars.

    In a telescope Mars is about 9 arcseconds wide, big enough for telescopes to give glimpses of its surface features. Mars is on its way to an apparent diameter of 15.1″ when closest to Earth in mid-April.

    No, the Great Red Spot hasn't shrunk. That gray-outlined orange oval that just crossed Jupiter's central meridian is Oval BA, once white and now nicknamed "Red Spot Junior." It's in the South Temperate Zone; south here is up. Io is about to pass behind the planet's western limb.

    The System II longitude of the central meridian was 349° when Christopher Go in the Philippines took this image on February 1st.

    Alan MacRobert

    Jupiter (magnitude –2.6, in Gemini) dominates the eastern sky in early evening. It crosses nearly overhead (for mid-northern observers) around 9 or 10 p.m.

    In a telescope Jupiter remains a big 46 or 45 arcseconds wide. For lots about observing Jupiter see the January Sky & Telescope or our brief online article Jupiter: Big, Bright, and Beautiful.

    Saturn (magnitude +0.5, in Libra) rises around 1 or 2 a.m. and is high in the south at dawn. By then it's far to the left of Mars and Spica, and less far to the upper right of Antares. Saturn is nearing western quadrature (90° west of the Sun).

    Uranus (magnitude 5.9, in Pisces) can still be located in the west-southwest right after dark. Finder chart.

    Neptune is disappearing into evening twilight.


    All descriptions that relate to your horizon — including the words up, down, right, and left — are written for the world's mid-northern latitudes. Descriptions that also depend on longitude (mainly Moon positions) are for North America.

    Eastern Standard Time (EST) is Universal Time (UT, UTC, or GMT) minus 5 hours.


    Like This Week's Sky at a Glance? Watch our SkyWeek TV short, also playing on PBS.


    To be sure to get the current Sky at a Glance, bookmark this URL:
    http://SkyandTelescope.com/observing/ataglance?1=1

    If pictures fail to load, refresh the page. If they still fail to load, change the 1 at the end of the URL to any other character and try again.

  • COMMENT